1. Technical Field
This invention relates generally to gas turbine engines and particularly to a tie shaft arrangement for gas turbine engine rotors.
2. Background Information
Gas turbine engines such as those which power aircraft and industrial equipment employ a compressor to compress air which is drawn into the engine and a turbine to capture energy associated with the combustion of a fuel-air mixture which is exhausted from the engine's combustor. The compressor and turbine of the engine typically comprise a multiplicity of airfoil blades which are mounted on a plurality of disks. The compressor disks and blades are rotationally driven by rotation of the engine's turbine. It is a well-known practice to employ longitudinal tie shafts to react the aerodynamic loading of the turbine and compressor blades by air and combustion gases acting thereon. It is a well-known prior art practice to employ a single tie shaft to axially couple the compressor and turbine bladed disks. As part of the tie shaft's function of reacting longitudinal aerodynamic loads on the compressor and turbine blades, the tie shaft must axially maintain axial preloads of the compressor and turbine disks. However, due to the extreme differences in aerodynamic loading of the compressor blades and turbine blades, the axial preloading requirements of compressor and turbine disks are extremely different and therefore, optimally preloading compressor and turbine bladed disks with a single tie shaft are difficult to achieve. Accordingly, there exists a need for a gas turbine engine rotor tie shaft arrangement wherein bladed disks of the engine's compressor and turbine may be independently axially preloaded to optimum levels.